Mat forming apparatus and method



Dec. 3, 1968 D, SANGESAND ET AL 3,413,688

MAT FORMING- APPARATUS AND METHOD Filed Jan. 30, 1967 2 Sheets-Sheet l lv I 1 Donald asangesand Dale L.Schuber+ BY JNVENTORS f JO; 8 iii Q Q EA'Hy.

Dec. 3, 1968 D SANGESAND ET AL 3,413,688

MAT FORMING APPARATUS AND METHOD Filed Jan. 30, 1967 2 Sheets-Sheet 2 iv i I i T .11 I ,1 1

llllll] lllllllll Donald LI. Sangescmcl Dale L. Schub JNV NTORS B Y EUnited States Patent 3,413,688 MAT FGRMING APPARATUS AND METHOD DonaldA. Sangesand and Dale L. Schubert, Tacoma, Wash., assignors toInternational Design Corporation, Tacoma, Wash, a corporation ofWashington Filed Jan. 30, 1967, Ser. No. 612,456 2 Claims. (Cl. 19-155)ABSTRACT OF THE DISCLOSURE Felted mats useful in the production of woodcomposition board are produced by felting lignocellulose particles on aforming screen in a felter provided with longitudinally extendingdeckles positioned a spaced distance inwardly from the side edges of thescreen. The particles are deposited on both sides of the deckles,forming a felted mat having separate central and marginal sections. Themarginal sections are removed selectively, leaving a center sectionhaving sharply defined side edges of uniform thickness. The centersection then may be hot pressed into a composite board having uniformproperties across its width.

Background of the invention This invention relates to apparatus andmethod for forming felted mats having sharply defined side edges ofuniform thickness. It relates particularly to apparatus and method forproducing felted mats of lignocellulosic pieces, useful in theproduction of wood composition board.

In the manufacture of wood composition board, it is usual practice toform a felted, binder-containing mat of wood fibers, chips, flakes,particles milled shavings or bagasse and then to press the mat until thedesired degree of consolidation has been achieved. A difliculty inherentin this procedure is that of providing a mat of uniform thickness, adesirable quality since non-uniformity of mat thickness is reflected innon-uniformity of density and other properties of the finishedconsolidated product.

It is particularly difiicult to provide a mat of uniform thickness usingthe various high-capacity continuous felters, in part because of theirregular action of the felters and in part because of the inherenttendency of the finely divided lignocellulosic felting stock to produceundesirable irregularities when deposited into a mat.

This difliculty is observed particularly in the operation of thecommonly used wig-wag type felters wherein the material to be felted ispassed rapidly through an oscillating spout and deposited on a movingconveyor between longitudinally arranged side plates, or deckles. Themat formed by such a felter may be non-uniform along its side edges,since the spout motion reverses at the end of each stroke. Also, thematerial being felted tends to hang up on the side walls of the deckles,dropping down on the margins of the mat at irregular intervals whenevera sufficient weight has accumulated.

The conventional manner of correcting this difficulty by scalping theupper surface of the mat is not a complete success. Even though scalpingresults in the formation of a mat of uniform thickness, it still may beof non-uniform density since the edge portions of the mat have beenconsolidated irregularly by the weight of the accumulated material.

It is a general object of the present invention to provide apparatus andmethod for overcoming the foregoing deficiencies of the feltingapparatus and producing as a final product a mat or felt of uniformthickness and density which may be consolidated to form a final productof uniform properties.

Still a further object of this invention is the provision of feltingapparatus which is of simple, inexpensive construction and characterizedby trouble-free operation.

In the drawings:

FIG. 1 is a view in side elevation, partly in section, of feltingapparatus employed in the manufacture of felted mats having uniform sideedges by the method of the present invention;

FIG. 2 is a sectional View taken along line 22 of FIG. 1;

FIG. 3 is a detail plan view further illustrating the apparatus of FIGS.1 and 2 and illustrating in particular the means employed for producingsharply defined, uniform, mat side edges;

FIG. 4 is a fragmentary plan view illustrating alternate means forproducing sharply defined mat side edges;

FIG. 5 is a sectional view taken along line 55 of FIG. 4; and

FIG. 6 is a fragmentary view of still another means for producing a matwith sharply defined side edges.

Generally stated, the mat forming apparatus of our invention comprises atraveling endless conveyor with matforming means arranged over theconveyor for depositing a continuous mat thereon. Mat divider means arepositioned longitudinally of the conveyor beneath the mat forming meansa spaced distance inwardly from the longitudinal side edges of theconveyor.

The divider means acts during the operation of the mat forming means todivide the mat into a central section and longitudinal marginal sectionsphysically apart from the central section. Separating means arepositioned adjacent the conveyor means downstream from the mat formingmeans for separating the marginal mat section from the central matsection.

In a preferred form of the invention the divider means may comprise oneor more deckle plates positioned longitudinally of the conveyor andarranged in such a manner that as the lignocellulosic particles aredriven downwardly upon the conveyor, those forming the central sectionof the mat are deposited inside the deckles while those forming thelongitudinal side margins of the mat are deposited outside the deckles.Then as the composite mat formed in this manner is conveyed along theconveyor, the separate mat marginal sections are guided away from thecentral section, thereby leaving a central section having uniform,sharply defined side edges.

Considering the foregoing in greater detail and with particularreference to the drawings:

The raw material which may be employed in the herein described matforming apparatus broadly comprises any material of the class from whichfelted mats are formed. Thus it may comprise plant material such asbagasse or straw reduced to the form of small pieces. Preferably,however, it comprises wood in the form of fibers, chips, shavings orflakes, to be used in the manufacture of wood composition board.

The raw material is mixed with a suitable portion of a suitable binderand is fed to felting apparatus such as the wig-wag or oscillating-spouttype felter illustrated in FIGS. 1 and 2. In such an apparatus a felterbox or housing 10 is fed with the felting furnish from the transitionsection of air conveying duct 12 communicating with the furnish source.Duct 12 delivers the furnish into an oscillating spout 14, the upper endof which is mounted on a shaft 16 journaled in bearings 18 and driven inreciprocating, oscillating movement by drive means not illustrated.

Spout 14, moving in characteristic wig-wag fashion, delivers acontinuous flow of raw material between felting box side plates 20having downstream extensions 21 arranged along the longitudinal sideedges of an endless traveling conveyor 22. The latter preferablycomprises an endless screen or other foraminous member reeved about anddriven by suitably positioned pulleys, one of which 'is indicated at 24.The screen traverses a suction box 26 located below spout 12 andcreating an air flow which assists in depositing a felted mat 30 on thescreen.

As indicated above, because of the eccentric motion of sprout 14, andbecause of fall off of accumulated material from side walls of thefelting box, the longitudinal margins a of the felt may be thicker andless uniform than the central portion 30b thereof. Accordingly means areprovided for forming and maintaining the side margins separate and apartfrom the centnal portion and thereafter guiding them away from thecentral portion to leave the latter as a residue having the desiredmarginal characteristics.

The form of the invention illustrated in FIGS. 1, 2 and 3 for performingthis function comprises mat divider means in the form of deckle plates32 having beveled upper edges positioned longitudinally of the conveyorbeneath the mat-forming means, a spaced distance inwardly from thelongitudinal side edges of the conveyor. The deckle plates aremaintained and supported in this position by suitable means such as, forexample, brackets fixed to the respective ends of the felting box.

As the particles are driven downwardly (FIG. 2), those forming themarginal portions of the mat fall outside of deckle plates 32 to formthe above noted marginal portions 30a which are kept separate fromcentral portion 30b. All three portions travel together on the conveyor,however, and together pass outside of the felter as is shownparticularly in FIG. 1.

Immediately upon leaving the felter, the mat is scalped to uniformthickness by means of conventional motor driven scalping roll 36. Thescalped material is disintegrated by picker roll 33 as it is exhaustedthrough vacuum conduit 40.

The leveled mat, still in three sections, then passes to divider meansillustrated in FIG. 3 and having for its purposes guiding the mat sidesection 30a laterally away from central section 3012.

To this end angularly arranged guide plates 42, which may be formed asoutwardly diagonal extensions of deckle plates 32, are positioned insuch a manner as to act as plows, guiding the marginal portions 30a ofthe mat outwardly and thus separating them from the central portion 30bthereof. Associated with guide plates 42 are a motor drivendisintegrating roll 44 and a vacuum collector 46 which disintegrate andconvey away, respectively, the marginal portions and return thedisintegrated material to the feed source.

Alternate means for separating marginal side portions 30a from thecentral portion 30b are shown in FIGS. 4 and 5.

In this form of the invention a suction box 50 is placed over themargins of the mat at a location downstream from the felter. This unitis arranged to suck away the undesired marginal mat portions 30a,thereby separating them from the central portion 30b and returning themto the feed source through duct 52.

Yet another means for dividing the irregular margin portions 30a fromthe desired mat portion 30b is illus trated in FIG. 6.

In this form of the invention deckle plates 32 are extendedsubstantially to the end of endless felting screen 22. A transfer plate58 is aligned with screen 22 and overlaps the screen at its downstreamend. It has a width which is equal substantially to the width of centralsection 30b of the mat with which it registers. It communicatesdownstream with an off bearing conveyor, not illustrated. Afunnel-shaped collector 60 is positioned beneath each of the outer endsof screen 22, below and downstream from roll 24. It communicates with asuction duct 62 which returns to the feed source mat margins 30a as theydrop Off the end of roll 24 and are collected in funnel 60.

4 Operation The operation of all of the forms of the inventionillustrated herein is essentially similar. In all of them, the materialis felted onto a continuously moving endless screen 22 in a feltingchamber 10 provided with longitudinally extending bafiies 32 positioneda spaced distance inwardly from the side walls 20 of the feltingchamber. The mat thus is formed in three sections, two marginal sections30a which may be of non-uniform thickness and density, and a centralsection 3012 of more uniform properties.

Though physically separated from each other, these three sections movetogether out of the felting chamber, beneath scalping roll 36, and tomeans for separating the marginal sections 30a from central section3011. In the FIG. 3 form of the invention, the separating means comprisediagonal guide plates or plows 42 which guide the margins away from thecenter section. In the FIGS. 4 and 5 form of the invention theseparating means comprise suction box 50 which sucks the margins awayfrom the central section. In the embodiment of FIG. 6, the separatingmeans comprise transfer plate 58 of predetermined width whichselectively transfers the central section 30b of the mat to theoffbearing conveyor, leaving side sections 30a to gravitate into funnel60.

In all cases the side margins thus are separated from the centralsection, leaving the latter with sharply defined side edges of uniformthick-mess and density, well suited for transfer to the hot press forthe production of a superior grade of wood composition board.

It "is to be understood that the forms of our invention herein shown anddescribed are to be taken as preferred examples of the same and thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of our invention or thescope of the subjoined claims.

Having thus descirbed our invention, we claim:

1. Mat forming apparatus comprising:

(a) a traveling endless conveyor,

(b) mat forming means arranged over the conveyor for depositing acontinuous mat thereon,

(c) mat divider means positioned longitudinally of the conveyor beneaththe mat forming means a spaced distance inwardly from the longitudinallyside edges of the conveyor,

(d) the divider means acting during operation of the mat forming meansto divide the mat into a central section and longitudinal marginalsections physically apart from the central section but travelingtherewith on the endless conveyor,

(e) separating means positioned adjacent the conveyor downstream fromthe mat forming means for separating the marginal sections of the matselectively from the central section thereof, and

(f) mat transfer means at the downstream end of the conveyor means, themat transfer means having a width substantially equal to the width ofthe central mat section only, thereby selectively transferring thecentral mat section away from the longitudinal marginal sections.

2. The mat forming apparatus of claim 1 including gravitationalcollecting the separated marginal sections.

References Cited UNITED STATES PATENTS 3,057,022 10/1962 Bar et al19-155 3,071,822 1/1963 Meiler 19-156.3 3,145,825 8/1964 Carter 198-303,165,433 1/1965 MacKowicz 156-375 XR 3,187,386 6/1965 Schubert et al19-155 3,057,022 10/1962 Bar et a1 19-155 MERVIN STEIN, PrimaryExaminer.

IRA C. WADDEY, JR., Assistant Examiner.

